How to give a command to plotter to draw or cut image randomly

Need more details. Where are you stuck?

Hi
That depends on what plotter you are using. It is safe to say that whatever language your plotter is using it will be similar to HPGL or a clone of it. http://en.wikipedia.org/wiki/HPGL

The way to communicate with the plotter is usually via serial, virtual serial over USB or parallel port of your computer.

Here is a good starting point if your plotter is a Roland :

http://omar.toomuchcookies.net/node/2009/11/scavenged-pen-plotter-roland-dg-dxy-990/comment-page-1/

I haven't used plotters in years so this info may be outdated but it is certainly a good starting point.

As to the API there isn't one as such as the communication happens by directly talking to the device by either serial :

http://msdn.microsoft.com/en-us/library/system.io.ports.serialport(v=vs.110).aspx

or parallel port:

http://www.codeproject.com/Tips/441815/Parallel-Port-Control-with-Csharp-NET

Thanks